Stiffening portion of shoes



March 2, 1.954 BRQPH 2,670,483

STIFFENING PORTION OF SHOES Filed 001:. 5, 1951 Patented Mar. 2, 1954 UNITED STATES PATENT OFFI STIFFENING PORTION OF SHOES Application October 5, 1951, Serial No. 249,991

6 Claims. (CI. 11-146) v 1 This invention relates to a method of stifien- 'ing selected porti'ons of shoes, and more: particularly to a method of stiffening such portions by so treating stiffener material incorporated in limp condition into the shoe materials as to. convert the stiffener material to a stifi'er, but resilient condition.

In the manufacture of shoes, it is frequently desirable to provide a stiffener member within the shoe, for example, at the shank, toe or heel portions. One method of stiffening toe or heel portions has been to include between the layers of upper materials a preformed blank of fiber board. An advantageous method, disclosed, for example, in United States Letters Patent. No. 2,406,738 granted September 3, 1946 and United v States Letters Patent No. 2,539,608 granted January'30, 1951 both in the name of John J. Brophy, comprises the steps of incorporating into the upper materials, at any convenient time prior to lasting, alimp blank which is convertible to a stiffer, but resilient condition and converting the blank to such a condition by subjecting it to the heating effect of an alternating electric field following the lasting step. This method has provided many shoemaking advantages, for example, in added convenience of handling the upper materials prior to lasting and in enhanced-quality of the product resulting in part from the better lasting obtainable therewith. However, normally moist leather is susceptible to damage by heat and ha a dielectric loss in the same order of magnitude as many of the proposed stiffener blanks. Owing to these physical and'electrical characteristics of leather, the electric field must presently be applied within fairly critical powertime limits in order properly to convert the stif- 'ren'er blank without damage to the shoe. Further', whatever form of heat is employed, a large portion of the treatment cycle is occupied .in bringing the stiffener material up to "converting temperature and hence the treatment is not immediately effective to promote conversion;

Accordingly an object of the invention is the provision of an improved method of providing a stiffening portion in a shoe which willretain the advantages of the above dielectric process while overcoming attendant difliculties.

Another object of the invention is the provision of a method of stiffening a selected portion of a shoeby treating, for conversion to a stiller, but resilient mass, limp stiffener material incorporated into the shoe materials in. the selected area, in which method the treatment may be performed very rapidly without: damage to the shoe parts. I

In one aspect, the invention comprises a method wherein stiffener material is incorporated in limp condition into the shoe materials in the area to be stiffened, and the stiffener :material is converted to a stiffer, but resilient condition by subjecting it to "materialistic radiation such as high speed electrons. Materialistic radiation" as used herein, includes material radiatio in the sense used in, Pollard and Davidson, Applied Nuclear Physics, John Wiley and Sons 1942, pp. 10 et seq., and also includes X-rays. and gamma rays. Such. subjection in accordance with the present invention usually involves projecting such radiation through intervening shoe material, for example, through an outer layer of upper-leather, but such delicate and heat-sensitive materials are unharmed during the short timerequired for activation.

These and other features and advantages of the invention will'best be. understood from the following description taken in connection with the. accompanying drawings in which:

Fig. 1 is a perspective view illustrating the activation of stiffener material within the toe portion of a lasted shoe; and

Fig. 2 is an enlarged section through the toe of said shoe.

Referring to Figs. 1 and 2, the shoe It has incorporated in its upper at the toe in limp form, stifiener material, preferably in the form of, a limp stiffener blank {2. Various methods or preparing such blanks are disclosed in the patents referred to above. Typically, a blank may be out from a sheet comprising a porous base which has. been first impregnated with 'a solutionof asin'fiener composition and then dried. The. conversion step is illustrated diagrammatically in Fig. 1. The shoe. is. prepared by incorporating .a limp. stiffener blank in the. upper materials in the portion to he. stiffened and lasting the upper overan. insole. If the shoe upper materials include a lining, this may be adhcsively secured to the stiffener blank at a. convenient time. prior to lastin for example. y pressure a n ng. a blank together momentarily against a heatedsurface to. apply a little heat through, the lining. The toe of the lasted shoe ll) is shown subjected to a beam IA of hi h-speed el ctron from a source it. Apparatus of various types for proriding a beam of such. electrons is commercially available. and being well-known, a particular source will not be described here. Such a beamis "considered herein ascomprising electron radia- .tion, -"v

upper or any other intervening material and traverse the stilfener material. I have found voltages from about 0.4 to 3 million volts to be very satisfactory for treating stiffening material beneath leather, but higher or lower voltages may be used ascircumstances warrant- If it is desired to treat the blank at minimum voltage, the shoe may be rocked or tilted during subjection to the beam so that the sides and feather edge areas iii are presented to the beam. I have found, however, that at 3 million volts, these areas are completely converted by a beam directed toward the top of the toe, presumably by secondary electrons produced by ionization of the air adjacent to these areas.

Compositions suitable for preparing a stiffener blank which is initially limp but convertible to a resilient condition in accordance with the present invention may comprise, for example, a polymerizable compound, preferably, a polyunsatu- 3 rated ester of the type disclosed in United States Letters Patent No. 2,155,590 granted April 25, 1939, on an application filed in the name of Benjamin S. Garvey. Commercially available materials containing esters of this type include various so-called unsaturated polyester resins:

Plaskon 920/2 made by Libby-Owens-Ford Glass Company, Toledo, Ohio; Paraplex P-43 and P-13 made by Rohm and Haas, Philadelphia, Pennsylvania; Laminac 4-201 and 4-128 made by American Cyanamid and Chemical Corporation, Plastics Division, New York, New York; Vibrin 120 and 1305'made by the Naugatuck Chemical Company, Naugatuck, Connecticut; and Castolite made by the Castolite Company, Woodstock, Illi- Example I A shoe was prepared by incorporating into the upper in the toe region a stiffener blank comprising a single nap cotton flannel impregnated to comprise 80 per cent solids of the following stiffener composition:

Parts by weight Vinylite VYHH 30.5 Polyethylene glycol 200 dimethacrylate monomer 15.25 Benzoyl peroxide 0.15 Tricresyl phosphate 0.15

Acetone 57 p-Phenyl phenol (inhibitor) 0.076

Vinylite VYHH is a copolymer of vinyl chloride andvinyl acetate comprising about 15 per cent vinyl acetate and is produced byCarbide and Carbon Chemicals Corporation of New York. The polyethylene monomer is an ester of methacrylic acid and polyethylene glycol 200 obtained from Carbide and Carbon Chemicals Corporation of New York. The lasted shoe was placed on a conveyor belt with the upper up and thereby moved at 0.4 inch per second beneath the window of an electron accelerator of the type disclosed in United States Letters Patent No. 1,991,236 issued February 12, 1935, in the name of Robert J. Van

'de Graaff for an exposure of about 10 seconds at a distance of 40 centimeters from the window.

4 The current of the beam was microamperes, corresponding to a density of about 1.46 microamperes per square centimeter, and the voltage was 3 million volts.

The box toe was exceedingly well converted in a very uniform manner over its entire surface even in the feather line region which was not in the direct path of the beam and with no apparent deleterious effect on either the upper leather or any other shoe component.

Example II The procedure of Example I was carried out with a stiffener blank impregnated with a stiffener composition which was similar to that of Example I, but in which the benzoyl peroxide was omitted. After subjection to the beam, the toe was well and uniformly converted.

Example III A quantity of Vibrin 1305 which has a wax-like consistency at room temperature, was warmed to 50-60" C. at which temperature the viscosity was reduced sufficiently to impregnate a double nap flannel. The impregnated flannel was allowed to cool, and a box toe blank was cut from it and incorporated in the upper of a shoe which was then lasted.

The blank was then treated as described in Example I, producing a very satisfactory box toe.

Example IV Three parts by weight of Atlac 382, an unsaturated alkyd resin made by the Atlas Powder Company of Wilmington, Delaware, and one part of diallyl phthalate were dissolved in four parts of benzene. A double nap flannel was impregnated with this solution and dried. A box toe blank cut from this impregnated flannel was incorporated in the toe of a lasted shoeandthe blank treated as described in Example I, producing a very satisfactory shoe.

Example V A limp box toe blank made as in Example I was subjected to the beam from the electron accelerator at 1.5 million volts for a period of 2:1 seconds. The blank was thereafter found to be very resilient.

Example VI A limp box toe blank was prepared as in Example II. After treatment at 1.5 million volts for 211 seconds, it was converted to a resilient condition.

While I have disclosed the use of an electron beam for treating the convertible stiffener material, it will be understood that the stiffener material may be subjected, for treatment purposes, to other forms of materialistic radiation in the nature of X-rays, gamma rays, protons, deuterons, neutrons, ions and alpha particles.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. The method of producing a stiffening portion in a shoe comprising the steps of incorporating in a selected part of a shoe, in limp form, stiffener material convertible through polymerization to a stiffer, but resilient resinous condition, and subjecting the stiffener material to materialistic radiation to effect such conversion.

2. The method of claim 1 in which the radiation is material radiation. 1

3. The method of claim 1 in which the radiation is electron radiation.

4. The method of producing a stifiening portion in a shoe comprising the steps of incorporating in a selected portion of a shoe, in limp form, stiffener material comprising an unsaturated ester and subjecting the stiffener material to materialistic radiation to convert it to a stifier, but resilient condition.

5. The method of claim 4 in which the radiation is material radiation.

6. The method of claim 4 in which the radiation is electron radiation.

JOHN J. BROPHY.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date Long Aug. 11, 1931 Newton May 2, 1933 Garvey Apr. 25, 1939 Brasch Oct. 21, 1947 Brophy Jan. 30, 1951 

